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United States Patent | 5,228,751 |
Ramsden, Jr. | July 20, 1993 |
Apparatus for measuring the degrees of roll of the body of a longwall shearing machine and providing signals proportional to the roll angle which are used to control drum cutting positions for controlling roof and floor horizons of a coal tunnel.
Inventors: | Ramsden, Jr.; John W. (Huntsville, AL) |
Assignee: | American Mining Electronics, Inc. (Huntsville, AL) |
Appl. No.: | 771771 |
Filed: | October 4, 1991 |
Current U.S. Class: | 299/1.6; 299/42 |
Intern'l Class: | E21C 035/12; E21C 035/24 |
Field of Search: | 299/1.1,1.2,1.6,42 |
4371209 | Feb., 1983 | Alford et al. | 299/1. |
4634186 | Jan., 1987 | Pease | 299/1. |
4643482 | Feb., 1987 | Wolfenden | 299/1. |
Foreign Patent Documents | |||
2027548 | Feb., 1980 | GB | 299/1. |